It is frequently desired to for aluminum within high aspect ratio contact openings during semiconductor fabrication. The contact openings ex tend through, for example, an insulative material. The aluminum functions as a conductive metal contact within the contact openings. The aluminum also generally extends beyond the contact openings to form wiring interconnect layers which electrically connect the metal contacts within the contact openings to other circuitry. The aluminum extending beyond the contact openings can lie over the insulative material through which the contact openings are formed. Unfortunately, if aluminum is deposited over a material there will frequently be stress-induced voids developed along edges of the deposited aluminum. It would be desirable to develop methods of forming aluminum wherein stress-induced void formation is substantially avoided.
A recently developed method of depositing aluminum is a so-called cold wall chemical vapor deposition (CVD) process, which can use, for example, dimethyl aluminum hydride (DMAH) as an aluminum precursor. The chemical vapor deposited aluminum nucleates better to titanium nitride (TiN) than to many other materials. Accordingly, a TiN layer is frequently provided prior to chemical vapor deposition of aluminum.